In my code, there is an memory leak, when the Keyboard appears for the first time when I am about to enter values in the UITextField. Can someone please give me some idea about this.
In the Interface File
IBOutlet UITextField *userEmail;
#property (nonatomic, retain) IBOutlet UITextField *userEmail;
Implementation File
#synthesize userEmail;
- (void)dealloc
{
[userEmail release];
}
- (void)viewDidUnload
{
self.userEmail = nil;
}
-(IBAction) emailOver:(id)sender{
[sender resignFirstResponder];
}
In the one of the functions NSLog(#"User Email: %#",[userEmail text]); Memory Leak occurs when the keyboard appears for the first time Do I have implement UITextFieldDelegate? Thanks
Consider that there's a bug in the iPhone simulator: if you write an almost empty project, putting only a UITextField in the XIB, and no code, you'll have a leak when you tap on the UITextField. On the contrary, if you try to build and run on the device, you'll have no leak. So It may be your case!! Give it a try, and let us know..
One problem is that your dealloc method is missing the MANDATORY [super dealloc] line.
- (void)dealloc
{
[userEmail release];
[super dealloc];
}
You don't need IBOutlet defined twice. One or the other should do.
UITextField *userEmail;
#property (nonatomic, retain) IBOutlet UITextField *userEmail;
I don't see anything else in your code that would cause a problem. What other methods do you have in your #implementation file.
I think you're right caprosky. Using a very simple test project I've Run With Monitoring Tools -> Leaks and as soon as I click on UITextField there is a memory leak that rises continuously.
I'll forget this for now and keep it in mind next time I'm using a UITextField (no
Related
I'm new at objective c, I was playing with labels buttons and textboxes, I've a label, text box and two buttons(Add, Clear),
what I want to do is, write something in the textbox and when press to "add" button I want the text to appear on the label , and the clear button should clear label and the text box
I've ran the program and the build is succeed however when i write some text and press return button nothing happens, the virtual keyboard still stays there and text doesn't appear on the label, my codes are as follows:
in the .h file
#interface ViewController : UIViewController
#property (retain, nonatomic) IBOutlet UILabel *label;
#property (retain, nonatomic) IBOutlet UITextField *txtbox;
#property (retain, nonatomic) IBOutlet UIButton *btnadd;
#property (retain, nonatomic) IBOutlet UIButton *btnclear;
- (IBAction)btnadd:(id)sender;
- (IBAction)btnclear:(id)sender;
- (IBAction)txtbox:(id)sender;
in the .m file
#implementation ViewController
#synthesize label,txtbox,btnadd,btnclear;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (void)dealloc {
[label release];
[txtbox release];
[btnadd release];
[btnclear release];
[super dealloc];
}
- (IBAction)btnadd:(id)sender {
label.text = (txtbox.text);
}
- (IBAction)btnclear:(id)sender {
txtbox.text=#"";
label.text=#"";
}
- (IBAction)txtbox:(id)sender {
}
#end
I would really appreciate if someone helps, thanks in advance
P.s : what is the code to end the program if incase I add an exit button?
Thanks again,
Asim Gunduz
Have you linked everything correctly in your .xib/storyboard?
Read this on how to properly handle the return key.
You should not exit an app with a button. The only way to close your app should be pressing the home button.
However, you could use
exit(0);
the code looks fine, but you can try these tutorials,
Linking the IBOutlet and IBAction
Hiding Keyboard
I have noticed that the memory usage of a program I wrote, keep increasing over time. XCode's instruments shows no memory leak, yet you can see the heap stack growing over time..
Upon investigation, a lot of the memory usage come from the IBOutlet UI objects. The interface is build with Interface Builder.
Typical usage would be like:
header:
#interface HelpViewController : UIViewController <UIWebViewDelegate> {
IBOutlet UIWebView *webView;
IBOutlet UIBarItem *backButton;
IBOutlet UIBarItem *forwardButton;
NSString *URL;
IBOutlet UIActivityIndicatorView *spin;
}
#property (nonatomic, retain) NSString *URL;
And for the usage :
- (void)webViewDidStartLoad:(UIWebView *)mwebView {
backButton.enabled = (webView.canGoBack);
forwardButton.enabled = (webView.canGoForward);
[spin startAnimating];
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
backButton.enabled = (webView.canGoBack);
forwardButton.enabled = (webView.canGoForward);
[spin stopAnimating];
}
Looking at the heap stack, you find that the UIActivityIndicatorView *spin object isn't properly deallocated, and its memory footprint will keep growing.
However, if I change the code to:
header:
#interface HelpViewController : UIViewController <UIWebViewDelegate> {
IBOutlet UIWebView *webView;
IBOutlet UIBarItem *backButton;
IBOutlet UIBarItem *forwardButton;
NSString *URL;
UIActivityIndicatorView *spin;
}
#property (nonatomic, retain) NSString *URL;
#property (nonatomic, assign) IBOutlet UIActivityIndicatorView *spin;
And in the code I do:
synthesize spin;
- (void)webViewDidStartLoad:(UIWebView *)mwebView {
backButton.enabled = (webView.canGoBack);
forwardButton.enabled = (webView.canGoForward);
[self.spin startAnimating];
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
backButton.enabled = (webView.canGoBack);
forwardButton.enabled = (webView.canGoForward);
[self.spin stopAnimating];
}
Nothing more, nothing else, then the heap stack doesn't grow anywhere as much.. and the UIActivityIndicatorView object doesn't leave any stuff behind
I can't figure out why it would make a difference here having an assign property or not, it just doesn't make sense ! Unless I massively misunderstood what's happening.
Any explanations would be welcomed..
Thanks
You need to release the objects in the dealloc method:
-(void)dealloc {
[webView release];
[backButton release];
[forwardButton release];
[URL release];
[spin release];
[super dealloc];
}
The reason why the problem doesn't occour in your second version is, that you set the property with the attribute assign, usually you should use retain for "object-properties" assign is usually used for the basic datatypes like int, float, bool etc...
EDIT:
to the part with retain and assign, afaik the behaviour is the following:
If the property is made with assign, then setting
self.thatVariable = something;
would be the same as:
thatVariable = something;
if you used retain it would be the same as:
[thatVariable release];
thatVariable = [something retain];
So if you used assign for variables that hold pointers to objects you can't be sure, that your object isnt deallocated somewhere else, which would result in a bad access.
Afaik the only reason to use assign with object is to get a weak reference. If you have to object which would both retain each other, none of it would ever get released. so thats a spot where you would use assign for objects. (f.e. often in the delegate-pattern. the object would retain it's delegate and the delegate would retain the object. In this case the delegate is often assigned)
I am new to objective C and I have a c++ background. I want to display a value in the label on the screen. I am calling the label value from the MainView.m. However, the label becomes blank after I click a button instead of printing a value. What is the problem? Here is the code.
MainView.h
#interface MainView : UIView {
int a;
}
-(int) vr;
#end
MainView.m
-(int) vr
{
return 100;
}
#end
MainViewController.h
#interface MainViewController : UIViewController {
IBOutlet UILabel *myLabel;
NSMutableString *displayString;
MainView *view1;
}
#property (nonatomic, retain) UILabel *myLabel;
#property (nonatomic, retain) NSMutableString *displayString;
(IBAction)showInfo;
(IBAction) pressButton:(id) sender;
#end
MainViewController.m
#synthesize myLabel, displayString;
-(IBAction) pressButton:(id) sender{
[displayString appendFormat:#"%i", view1.vr];
myLabel.text = displayString;}
- (void)viewDidLoad {
view1 = [[MainView alloc] init];
[super viewDidLoad];}
- (void)dealloc {
[view1 dealloc];
[super dealloc];}
I have not mentioned code that had been auto generated. This is enough to get the whole picture. I tried a lot to debug this thing. I believe that IBAction carries out direct command such that
myLabel.text = #"string";
but it does not invoke any method or class. Any subtle ideas? Thanks.
Few issues:
1
In MainView.h you declare -(id) vr;
And in MainView.m it returns int.
2
Maybe pressButton is not connected to the right event in Interface Builder (it is usually touch up inside).
Try to write to log in this method.
3
Maybe myLabel is not connected to the label in the Interface Builder.
Try to set tome hard-coded string to label's text property.
4
Do you initiate view1 in some place?
Can you post this piece of code too?
5
You can use [displayString appendFormat:#"%i", view1.vr];...
EDIT (due to changes in question):
6
The line [super viewDidLoad]; should be the first line inside viewDidLoad.
7
[view1 dealloc]; - never call dealloc directly on objects. Call release instead. The only place, where you can and should use dealloc is the line [super dealloc]; inside dealloc method.
8
When you format your question/answer in Stack Overflow, remember that each code line should start with at least 4 spaces (or tab). Try reformatting you question by adding 4 spaces in the beginning of each code line.
9
I think that displayString is not initiated. Add the next line in the viewDidLoad: displayString = [NSMutableString new];
Hey there, I'm a designer thats really new to programming with xcode or Objective-C in general. I'm trying to create a few simple apps to try to get a better hang on programming the iPhone. Currently, I'm working on a very basic app which has 3 textfields, a name field and two number fields, and when you click the button, it shows in the label "name, the answer is answer" problem is, when i click the button, nothing is appearing in the label.
im pretty sure i have the code done right, i may be mistaken, i think i might have missed an outlet or something silly of the like. this is the part i get really lost on. any suggestions?
the .h:
#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>
#interface fordaddyAppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
IBOutlet UITextField *name;
IBOutlet UITextField *myInt1;
IBOutlet UITextField *myInt2;
IBOutlet UILabel *sum;
IBOutlet UIButton *click;
}
#property (nonatomic, retain) IBOutlet UIWindow *window;
-(IBAction)click:(id)sender;
#end
the .m:
#import "fordaddyAppDelegate.h"
#implementation fordaddyAppDelegate
#synthesize window;
- (void)applicationDidFinishLaunching:(UIApplication *)application {
[window makeKeyAndVisible];
}
-(IBAction)click:(id)sender;
{
int sum;
sum = myInt1, myInt2;
NSLog (name, #", the answer is %i", sum);
}
- (void)dealloc {
[window release];
[super dealloc];
}
#end
and im terribly sorry in advance, the preview doesnt look to pretty :/
your problem is that you are just writting a message to the console, not displaying the result in the label...
Here's what it should be:
- (IBAction)click:(id)sender {
int sum = [myInt1.text intValue] + [myInt2.text intValue];
label.text = [NSString stringWithFormat:#"%# the answer is %d", name.text, sum];
}
That makes a variable 'sum' which is the result of the integer values of the text fields being added together. you access the string of a UITextView by using the .text. Then you have to convert it into an integer for addition, so you call the intValue method on it. You then make an NSString with stringWithFormat, and have it contain the name.text and the sum. I would highly recommend doing some more reading about Objective-C in general before you start with all this GUI stuff... just a suggestion.
Your problem is this:
int sum;
sum = myInt1, myInt2;
sum is an integer. myInt1 and myInt2 are UITextFields. The comma does not do what you're expecting.
You need to extract the intValue from each of the textfields, and add them together using a "+" (just like you would with regular math).
As well as my question "Removing MKMapView Annotations causes leaks." I have discovered that if you create a view based project, add a UISearchBar and MKMapView into the view's NIB, wire up the delegates (I'm not creating any methods as we don't actually need to do anything to trigger the leaks), link in the MapKit and fire up the project, then simply clicking in the UISearchBar causes a 1k+ leak. This doesn't happen unless you have both UISearchBar and MKMapView in a view. I have the same issues when creating the views from code. I thought a NIB might behave differently, but it doesn't.
Is MKMapView leaky, or am I doing something wrong.
To replicate the issue with code try the code below - I created a new "view based application" project
TestMapViewFromCodeViewController.h
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h>
#interface TestMapViewFromCodeViewController : UIViewController {
UISearchBar *searchBar;
MKMapView *mapView;
}
#property (nonatomic, retain) MKMapView *mapView;
#property (nonatomic, retain) UISearchBar *searchBar;
#end
TestMapViewFromCodeViewController.m
- (void)viewDidLoad {
[super viewDidLoad];
UISearchBar * tmpSearchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0.0,0.0,self.view.frame.size.width,40.0)];
[self.view addSubview:tmpSearchBar];
[self setSearchBar:tmpSearchBar];
[tmpSearchBar release];
MKMapView *tmpMapView=[[MKMapView alloc] initWithFrame:CGRectMake(0.0,0.0,self.view.frame.size.width,self.view.frame.size.height)];
tmpMapView.showsUserLocation=FALSE;
[self.view insertSubview:tmpMapView atIndex:0];
[self setMapView:tmpMapView];
[tmpMapView release];
}
- (void)dealloc {
[mapView release];
[searchBar release];
[super dealloc];
}
Although I've retained the subviews with mapView and searchBar, this is probably unnecessary to replicate the issue.
In testing this code prior to publishing here I've just noticed that this leak does not occur in the simulator - only on my phone...
Yes.
There is a known leaks on 3.0's MKMapViews. The leak occurs when you deallocate the MKMapView This is fixed in later releases. The workaround is to have a single MKMapView and reuse it.
https://devforums.apple.com/message/129740#129740
For what its worth, there are similar related questions here:
https://stackoverflow.com/questions/5935243/mkmapview-rame-et-fuite-memoire-apple
Can the memory used by MKMapView be released some how?
MKMapView Memory Leak in iPhone Application